Demonstration of Choline Acetyltransferase of a Peripheral Type in the Rat Heart
Osamu Yasuhara 1*, Akinori Matsuo 1, Jean-Pierre Bellier 1 and Yoshinari Aimi 1
1 Molecular Neuroscience Research Center, Shiga University of Medical Science, Otsu, Shiga, Japan
* To whom correspondence should be addressed. E-mail: yasuhara{at}belle.shiga-med.ac.jp.
Submitted on September 10, 2006
Accepted on 16 November 2006
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Abstract |
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Cholinergic innervation of the heart has been analyzed using cholinergic markers including acetylcholinesterase, choline acetyltransferase (ChAT) and vesicular acetylcholine transporter (VAChT). In the present study, we demonstrate putative cholinergic nerves in the rat heart using an antibody to pChAT, which is the product of a splice variant of ChAT mRNA and preferentially localized to peripheral cholinergic nerves. Expression of mRNAs for pChAT and the conventional form of ChAT (cChAT) were verified in the rat atrium by RT-PCR. The localization of both protein products in the atrium was confirmed by Western blotting. Virtually all neurons and small intensely fluorescent cells in the intrinsic cardiac ganglia were stained immunohistochemically for pChAT. The density of pChAT-positive fibers was very high in the conducting system, high in both atria, the right atrium in particular, and low in the ventricular walls. pChAT- and VAChT-immunoreactivities were closely associated in some fibers and fiber bundles in the ventricular walls. These results indicate that intrinsic cardiac neurons homogeneously express both pChAT and cChAT. Furthermore, the innervation of the ventricular walls by pChAT- and VAChT-positive fibers provides morphological evidence for a significant role of cholinergic mechanisms in ventricular functions.
Key Words:
acetylcholine, acetylcholinesterase, choline acetyltransferase, cardiac neurons, nitric oxide synthase, tyrosine hydroxylase, vesicular acetylcholine transporter
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